These shields have a sticky back (3m double-sided tape - either foam tape which is thick, or clear tape which is thin). The surface should be cleaned - wax removed. Before positioning the shields, look at pictures of other Ferraris and determine the approximate location of the shield (do this for one side only). When you have determined approximately where you want the shield, take blue painter's tape and run it straight down the windshield pillar for a few feet. Next, measure a point (along the tape) from the end of the pillar to a spot where the top of the shield will be. Tape down, or mark the spot and apply the shield in the exact spot per measurements. Repeat exactly the same for the other side. Remove the blue painter's tape. Note- Make sure the shield is straight top to bottom by marking with a stabilo (or piece of tape) on the fender. Here is a generic ebay (no affiliation) description of the shields...
FERRARI FENDER WING SHIELDS 308,328,348,355,360,550,TR:eBay Motors (item 200383092086 end time Sep-15-09 00:14:48 PDT)